self leveling
- Thread starter lee_374355239
- Start date
No. By lifting the back end it just provides more available suspension travel, which may come in useful. However, for the sake of stability, one should always aim for the maximum noseweight that is permissble, whether self-levelling suspension is fitted or not.
Hi Lutz
I fully agree sls does nothing to help noseweight,and should not be viewed as quick fix . It certainly helps keep the vehicle attitude absolutely level when fully loaded and towing. Thus subject to using the correct noseweight it is a great asset to have. I have had it on my last two vehicles and as a tugger would not wish to be without it.
Cheers
Alan
I fully agree sls does nothing to help noseweight,and should not be viewed as quick fix . It certainly helps keep the vehicle attitude absolutely level when fully loaded and towing. Thus subject to using the correct noseweight it is a great asset to have. I have had it on my last two vehicles and as a tugger would not wish to be without it.
Cheers
Alan
Putting the suspension travel issue aside for a minute, keeping the car and or caravan absolutely level is only of cosmetic significance and has nothing to do with loading capacity. Nevertheless, self-levelling suspension is still a worthwhile option.
YES i have SLS it is standard fit on mercedes E Class estate ,it works very well ,it is one of the reasons i bought the car . I would say it brings the cars ride height up to the same level as when solo , so it helps braking and steering. But that is what it is meant to do.
It neither helps with the brakes nor with the steering. Both steering and brake behaviour and performance depend on the respective axle loads and ride height does not affect these.
Lutz
I am no scientist but I thought the point of sls was to keep the vehicle dynamics as if solo / unladen. Surely the aerodynamics and angles of universal joints must be better with sls rather than a saggy bum where everything is out of sink??
Why else do manufacturers fit it/
Cheers
Alan
I am no scientist but I thought the point of sls was to keep the vehicle dynamics as if solo / unladen. Surely the aerodynamics and angles of universal joints must be better with sls rather than a saggy bum where everything is out of sink??
Why else do manufacturers fit it/
Cheers
Alan
Certainly at the sort of speeds you encounter when towing, the small change in attitude is not going to make a significant difference to aerodynamic performance. The change in driveline angles in roll and on bumpy or undulating roads is also going to be much larger than the difference a low back end is going to make.
The big advantage of self-levelling suspension is that it prevents the suspension from bottoming out on bad roads and it can, in doing so, also improve handling, but only in extreme situations where the suspension would otherwise bottom out. Also, for older cars not fitted with manual or automatic headlamp beam adjusters, it prevents the headlamps from pointing to the sky when the boot is full.
The big advantage of self-levelling suspension is that it prevents the suspension from bottoming out on bad roads and it can, in doing so, also improve handling, but only in extreme situations where the suspension would otherwise bottom out. Also, for older cars not fitted with manual or automatic headlamp beam adjusters, it prevents the headlamps from pointing to the sky when the boot is full.
I agree with Lutz's initial answer that the noseweight should be the maximum permissible. There isn't usually an increase when self-levelling is chosen as an option.
Having recently changed to a car with self-levelling suspension I'd never go back to one without - for towing or general use.
It's main advantage is that the rear suspension geometry is always operating at it's designed position. Non-levelling suspension will be running high or low, dependent on load, with less than ideal camber and toe-in angles in many cases. Having a level car also means that the front suspension is running at it's designed angle, not pitch back or forth slightly.
Having recently changed to a car with self-levelling suspension I'd never go back to one without - for towing or general use.
It's main advantage is that the rear suspension geometry is always operating at it's designed position. Non-levelling suspension will be running high or low, dependent on load, with less than ideal camber and toe-in angles in many cases. Having a level car also means that the front suspension is running at it's designed angle, not pitch back or forth slightly.
Hi All
So does having SLS mean that because the front is not up & the car is level. That it reduces the front tyre scrabble because the front is at the normal drive height?
Cheers for now
Julian
So does having SLS mean that because the front is not up & the car is level. That it reduces the front tyre scrabble because the front is at the normal drive height?
Cheers for now
Julian
In all cases that I'm aware of the self levelling feature works only on the rear axle, where the biggest fluctuation in axle load is to be expected. I don't know of a car with self levelling suspension on the front axle too, but someone may put me right on this one.
Julian - if all the load is behind the rear axle, causing the front axle to lift, SLS won't alter the front suspension height, just the rear - that will improve suspension geometry slightly but won't counteract reduced grip at the front.
In any case, most cars with SLS also have traction control to stop the scrabbling.
In any case, most cars with SLS also have traction control to stop the scrabbling.
Hi All
I understand that there in no SLS on the front suspension. All I thought was if the car was level then the front wouldn't be so light.
I was looking at The Mondeo estate which does have the SLS but unfortunatley not TC as far as i know.
Cheers for now
Julian
I understand that there in no SLS on the front suspension. All I thought was if the car was level then the front wouldn't be so light.
I was looking at The Mondeo estate which does have the SLS but unfortunatley not TC as far as i know.
Cheers for now
Julian
In response to Lutz there are in fact several cars with "allround" self leveling suspension.
As an ex Allroad driver they definitely do and I believe the A8, Q7 and perhaps Q5 follow suit.
The Volvo equivalents may also do - but I dont know if they have Air suspension
As an ex Allroad driver they definitely do and I believe the A8, Q7 and perhaps Q5 follow suit.
The Volvo equivalents may also do - but I dont know if they have Air suspension
Hello Julian,
Using SLS simply raises the rear of the car by stiffening the rear suspension. No weight is transfered from the rear to the front axle so there is no real change to the downforce on the front wheels. The grip may improve but it will only be very mariginal resulting from the improved geometry when the body of the car is level.
Using SLS simply raises the rear of the car by stiffening the rear suspension. No weight is transfered from the rear to the front axle so there is no real change to the downforce on the front wheels. The grip may improve but it will only be very mariginal resulting from the improved geometry when the body of the car is level.
Hi all. How about spring assistors? Any good? I have a Volvo S80 and am thinking of fitting some, all advice appreciated.
I had self leveling suspension as a factory fitted option on my previous Volvo V70 (05 model). I don't have it fitted on my current V70 (08 new type). I know that the current V70 is a different car but I don't notice any difference whatsoever.
I've fitted shock absorbers to the caravan in between changing vehicles but I would suggest that it's more to do with loading the van and car correctly.
I've fitted shock absorbers to the caravan in between changing vehicles but I would suggest that it's more to do with loading the van and car correctly.
Paul,
You are correct, there are a number of manufacturers putting out models with such suspension, however those systems tend to be air suspension on more prestige models or marques.
Until recently I was towing with a Volkswagen Touareq V10, which had the full works when it came to air suspension. It was self levelling and I could dial in ride heights and comfort settings, or leave it on auto.
It would automatically the entire car to the road at higher speeds if required, it would lower the car to below ride height to allow easier egress and entry to the vehicle for eg., disabled owners, it had an extra high setting which could only be used in low ratio and intended for more extreme offroad use.
It was a dream with the caravan on the back, but I imagine a nightmare if it had gone wrong.
I don't miss it and I'm managing perfectly well on normal sprung suspension.
Ken.
You are correct, there are a number of manufacturers putting out models with such suspension, however those systems tend to be air suspension on more prestige models or marques.
Until recently I was towing with a Volkswagen Touareq V10, which had the full works when it came to air suspension. It was self levelling and I could dial in ride heights and comfort settings, or leave it on auto.
It would automatically the entire car to the road at higher speeds if required, it would lower the car to below ride height to allow easier egress and entry to the vehicle for eg., disabled owners, it had an extra high setting which could only be used in low ratio and intended for more extreme offroad use.
It was a dream with the caravan on the back, but I imagine a nightmare if it had gone wrong.
I don't miss it and I'm managing perfectly well on normal sprung suspension.
Ken.
Paul,
You are correct, there are a number of manufacturers putting out models with such suspension, however those systems tend to be air suspension on more prestige models or marques.
Until recently I was towing with a Volkswagen Touareq V10, which had the full works when it came to air suspension. It was self levelling and I could dial in ride heights and comfort settings, or leave it on auto.
It would automatically lower the entire car to the road at higher speeds if required, it would lower the car to below ride height to allow easier egress and entry to the vehicle for eg., disabled owners, it had an extra high setting which could only be used in low ratio and intended for more extreme offroad use.
It was a dream with the caravan on the back, but I imagine a nightmare if it had gone wrong.
I don't miss it and I'm managing perfectly well on normal sprung suspension.
Ken.
You are correct, there are a number of manufacturers putting out models with such suspension, however those systems tend to be air suspension on more prestige models or marques.
Until recently I was towing with a Volkswagen Touareq V10, which had the full works when it came to air suspension. It was self levelling and I could dial in ride heights and comfort settings, or leave it on auto.
It would automatically lower the entire car to the road at higher speeds if required, it would lower the car to below ride height to allow easier egress and entry to the vehicle for eg., disabled owners, it had an extra high setting which could only be used in low ratio and intended for more extreme offroad use.
It was a dream with the caravan on the back, but I imagine a nightmare if it had gone wrong.
I don't miss it and I'm managing perfectly well on normal sprung suspension.
Ken.
Self levelling suspension will not redistribute load on the front and back wheels. Just because self levelling prevents the nose from being up or the back end down doesn't mean that there is any more weight on the front axle or less on the rear.
When a caravan is loaded correctly and agreed, at the correct nose weight, that figure is at it's optimum when used at the correct height ie. The one that the towing vehicle tow bar height is set at.
As made clear (04/05) by John L's response to "Noseweight Question" in the 'Technical Section', due to the fulcrum effect, if the height of the caravan hitch is raised, the weight transposed through it is reduced and in a ridiculously extreme example, the rear of the caravan will drop to the floor with a negative weight value being put on the tow bar ie ;- Having the effect of lifting the rear wheels of the tow car.
If you weigh the noseweight of your van at it's normal towing height on say, a set of bathroom scales with a piece of wood cut to length to mirror your tow ball height, then remove the wood and weigh the nose weight at ground level direct on to the scales, the latter will provide a greater figure.
Therefore, if the tow bar is lowered to below it's normal towing height, the weight transposed through it will increase, as just described, and when the rear of the towing vehicle sags, the weight transposed through the hitch will increase.
The effect of any weight pushing down on the tow bar, has an effect on the towing vehicle, and again using a ridiculously extreme example, if you pushed down with enough force, the car would pivot around the rear axle and the front wheels of the tow car would lift clear of the ground.
Self levelling suspension, retains the optimum height of the hitch and therefore prevents the 'increase' in weight transfer as the hitch drops due to the effects of loading.
This allows the front wheels to remain in full contact with the road and therefore has an actual effect of transferring some of the load from the rear axle, back to the front axle.
With reference to the rather more complicated air suspension set ups, these also allow the transference of loads, not only from front to rear, but also from side to side.
When a vehicle corners, some of it's weight and the 'G' effects of cornering transfer to one side of the car or the other, depending on which direction you are cornering.
This is what gives body roll, however due to the suspension, the car body is allowed to tilt while the four wheels remain in contact with the road surface, allowing the car, under normal driving conditions to corner under control.
In extreme cornering, the effect of the body roll can be sufficient to lift the inside wheels from the road surface, reducing tyre grip and causing tyre squeal or eventually a skid or rollover if enough tyre contact is not maintained with the road surface or if the body leans too far.
The stiffer suspension seen on sports cars, along with other measures, reduces body roll and helps keep the car on an even plane when cornering at higher speeds.
The air suspension sensors on my last VW Toaureg automatically detected the amount of body roll and stiffened the suspension as required to help keep the car on a level plain, thereby transferring some of the sprung weight back to the opposite side of the car, reducing cornering effects and keeping the outer wheels in contact with the road surface and retaining that 'all essential' grip.
So in essence, self levelling is a benefit to driving and towing, including both handling and braking aspects, as a tyre that is losing traction with the road surface has a reduced braking efficiency and is less likely to keep the car on the road during cornering, however, self levelling will not allow you to exceed the recommended nose weights of your car or caravan.
PS. I do not usually drive or tow to the extremes cited above, they are purely examples.
As made clear (04/05) by John L's response to "Noseweight Question" in the 'Technical Section', due to the fulcrum effect, if the height of the caravan hitch is raised, the weight transposed through it is reduced and in a ridiculously extreme example, the rear of the caravan will drop to the floor with a negative weight value being put on the tow bar ie ;- Having the effect of lifting the rear wheels of the tow car.
If you weigh the noseweight of your van at it's normal towing height on say, a set of bathroom scales with a piece of wood cut to length to mirror your tow ball height, then remove the wood and weigh the nose weight at ground level direct on to the scales, the latter will provide a greater figure.
Therefore, if the tow bar is lowered to below it's normal towing height, the weight transposed through it will increase, as just described, and when the rear of the towing vehicle sags, the weight transposed through the hitch will increase.
The effect of any weight pushing down on the tow bar, has an effect on the towing vehicle, and again using a ridiculously extreme example, if you pushed down with enough force, the car would pivot around the rear axle and the front wheels of the tow car would lift clear of the ground.
Self levelling suspension, retains the optimum height of the hitch and therefore prevents the 'increase' in weight transfer as the hitch drops due to the effects of loading.
This allows the front wheels to remain in full contact with the road and therefore has an actual effect of transferring some of the load from the rear axle, back to the front axle.
With reference to the rather more complicated air suspension set ups, these also allow the transference of loads, not only from front to rear, but also from side to side.
When a vehicle corners, some of it's weight and the 'G' effects of cornering transfer to one side of the car or the other, depending on which direction you are cornering.
This is what gives body roll, however due to the suspension, the car body is allowed to tilt while the four wheels remain in contact with the road surface, allowing the car, under normal driving conditions to corner under control.
In extreme cornering, the effect of the body roll can be sufficient to lift the inside wheels from the road surface, reducing tyre grip and causing tyre squeal or eventually a skid or rollover if enough tyre contact is not maintained with the road surface or if the body leans too far.
The stiffer suspension seen on sports cars, along with other measures, reduces body roll and helps keep the car on an even plane when cornering at higher speeds.
The air suspension sensors on my last VW Toaureg automatically detected the amount of body roll and stiffened the suspension as required to help keep the car on a level plain, thereby transferring some of the sprung weight back to the opposite side of the car, reducing cornering effects and keeping the outer wheels in contact with the road surface and retaining that 'all essential' grip.
So in essence, self levelling is a benefit to driving and towing, including both handling and braking aspects, as a tyre that is losing traction with the road surface has a reduced braking efficiency and is less likely to keep the car on the road during cornering, however, self levelling will not allow you to exceed the recommended nose weights of your car or caravan.
PS. I do not usually drive or tow to the extremes cited above, they are purely examples.
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